Re: [syzbot] [ocfs2?] KASAN: use-after-free Read in ocfs2_claim_suballoc_bits

[syzbot <syzbot+5054473a31f78f735416@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: signed-integer-overflow in ip_idents_reserve

================================================================================
UBSAN: signed-integer-overflow in ./arch/x86/include/asm/atomic.h:165:11
-2082307266 + -1738913672 cannot be represented in type 'int'
CPU: 0 PID: 43 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
Call Trace:
 dump_stack+0xfd/0x16e lib/dump_stack.c:118
 ubsan_epilogue+0xa/0x30 lib/ubsan.c:148
 handle_overflow+0x192/0x1b0 lib/ubsan.c:180
 arch_atomic_add_return arch/x86/include/asm/atomic.h:165 [inline]
 atomic_add_return include/asm-generic/atomic-instrumented.h:73 [inline]
 ip_idents_reserve+0x14a/0x170 net/ipv4/route.c:521
 __ip_select_ident+0xe4/0x1c0 net/ipv4/route.c:538
 iptunnel_xmit+0x466/0x7b0 net/ipv4/ip_tunnel_core.c:80
 udp_tunnel_xmit_skb+0x1ba/0x290 net/ipv4/udp_tunnel_core.c:190
 send4+0x5d4/0xaf0 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0xcd/0x1c0 drivers/net/wireguard/socket.c:175
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x16b/0x280 drivers/net/wireguard/send.c:51
 process_one_work+0x85c/0xfa0 kernel/workqueue.c:2282
 worker_thread+0xa9b/0x1430 kernel/workqueue.c:2428
 kthread+0x360/0x3e0 kernel/kthread.c:328
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
================================================================================
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 0 PID: 43 Comm: kworker/u4:2 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: wg-kex-wg0 wg_packet_handshake_send_worker
Call Trace:
 dump_stack+0xfd/0x16e lib/dump_stack.c:118
 panic+0x2f0/0x9c0 kernel/panic.c:308
 check_panic_on_warn+0x95/0xe0 kernel/panic.c:228
 handle_overflow+0x192/0x1b0 lib/ubsan.c:180
 arch_atomic_add_return arch/x86/include/asm/atomic.h:165 [inline]
 atomic_add_return include/asm-generic/atomic-instrumented.h:73 [inline]
 ip_idents_reserve+0x14a/0x170 net/ipv4/route.c:521
 __ip_select_ident+0xe4/0x1c0 net/ipv4/route.c:538
 iptunnel_xmit+0x466/0x7b0 net/ipv4/ip_tunnel_core.c:80
 udp_tunnel_xmit_skb+0x1ba/0x290 net/ipv4/udp_tunnel_core.c:190
 send4+0x5d4/0xaf0 drivers/net/wireguard/socket.c:85
 wg_socket_send_skb_to_peer+0xcd/0x1c0 drivers/net/wireguard/socket.c:175
 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
 wg_packet_handshake_send_worker+0x16b/0x280 drivers/net/wireguard/send.c:51
 process_one_work+0x85c/0xfa0 kernel/workqueue.c:2282
 worker_thread+0xa9b/0x1430 kernel/workqueue.c:2428
 kthread+0x360/0x3e0 kernel/kthread.c:328
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
Kernel Offset: disabled
Rebooting in 86400 seconds..


Tested on:

commit:         d3d0b4e2 Linux 5.10.245
git tree:       https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git linux-5.10.y
console output: https://syzkaller.appspot.com/x/log.txt?x=165e9be2580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=39182a54870857eb
dashboard link: https://syzkaller.appspot.com/bug?extid=5054473a31f78f735416
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=15ba8c92580000